1. Technical Field
This invention relates to the making of cast metal parts with ceramic liners for automobiles and, more particularly, to (1) a method of forming a metal part having a breakage resistant ceramic liner comprising the steps of, forming a metal part having a mating surface for receiving the liner; forming a liner of a ceramic material containing pores; filling the pores with a pre-ceramic polymer resin; firing the pre-ceramic polymer resin (hereinafter used interchangeably with the term polymer-derived ceramic resin) saturated liner at a temperature which converts the resin into a ceramic within the pores, and, attaching the ceramic liners to the mating surface of the metal part; (2) to methods for accomplishing the same result comprising the steps of forming a liner of a ceramic material containing pores; filling the pores with a pre-ceramic polymer resin; firing the pre-ceramic polymer resin saturated liner at a temperature and for a time which converts the resin into a ceramic within the pores; positioning the liner within a mold for the metal part with the mating surface of the liner facing into a portion of the mold to be occupied by metal forming the part; and, filling the mold with molten metal to form the part with an integral, cast-in-place, ceramic insert; and, (3) to a method of forming fiber reinforced ceramic matrix composite (FRCMC) parts and liners comprising the steps of, forming a preform in the shape of the part from fibers of a generic fiber system (hereinafter used interchangeably with the term reinforcing fibers employable in fiber reinforced ceramic matrix composites; placing the preform in a cavity of a mold having the shape of the part; forcing a liquid polymer-derived ceramic resin through the cavity to fill the cavity and saturate the preform; heating the mold at a temperature and for a time associated with the polymer-derived ceramic resin which transforms the liquid polymer-derived ceramic resin-saturated preform into a polymer composite part; removing the polymer composite part from the mold; and, firing the polymer composite part in an inert atmosphere at a temperature and for a time associated with the polymer-derived ceramic resin which transforms the polymer-derived ceramic resin into a ceramic whereby the polymer composite part is transformed into a fiber reinforced ceramic matrix composite part.
2. Background Art
Operating temperatures of automobile and like internal combustion engines have increased for various reasons such as improved combustion efficiency and reduction of the fuel to air ratio (i.e. leaner burning engines) for the purposes of reducing emitted pollutants resulting from more complete burning of the fuel. Accordingly, there has been a corresponding need to protect metal parts subjected to these increased temperatures. An obvious approach tried with limited success in the prior art is to line the metal parts with ceramic. Thus, for example, we have an exhaust manifold 10 with a monolithic ceramic lining 12 as depicted in FIG. 1 and a power head 14 with a ceramic lining 12 as depicted in FIG. 2 being known in the prior art.
The problem of this prior art approach can be best understood with reference to FIG. 3. As can be seen in the enlarged drawing, the monolithic ceramic material of the lining 12 as employed in the prior art is a porous material having a multitude of pores 16 throughout. Thus, the lining 12 of the prior art is fairly delicate, with nominal erosion resistance, and is easily broken if the part is dropped, struck, or otherwise subjected to a large force. If the lining 12 of the power head 14 breaks and a piece falls off inside the operating engine, the inside of the cylinder of the engine will most likely be heavily scored by the hard ceramic edges bouncing about. For both the power head 14 and the exhaust manifold 10, any gap or break in the ceramic liner will eventually result in damage to or the destruction of the unprotected underlying metal. A crack through the exhaust manifold 10 or through the power head 14 typically will require complete replacement of the part.
Also, the lining of a part with the monolithic ceramic material according to prior art techniques can be a delicate, costly, and time-consuming process.
Wherefore, it is an object of the present invention to provide a ceramic lining for an automotive internal combustion engine part or the like which is toughened to resist breakage and erosion.
It is another object of the present invention to provide a method for applying a ceramic lining to an automotive internal engine part or the like, which is simple, inexpensive, and can be rapidly assembled so as not to impact the high rate manufacturing schedule associated with automotive components.
It is still another object of the present invention to provide a method for applying a ceramic lining to an automotive internal engine part or the like, wherein the lining is cast into the part as part of the molding process.
It is yet another object of the present invention to provide a method for creating fiber reinforced ceramic matrix composite preforms for use in lining automotive internal engine parts and making automotive internal engine parts.
Other objects and benefits of this invention will become apparent from the description which follows hereinafter when read in conjunction with the drawing figures which accompany it.